Industrial fermentation process for bacillus using partial harvest

A method for producing a protein of interest from a Bacillus host cell comprising the steps of:

• (a) inoculating a fermentation medium with a Bacillus host cell comprising an expression construct for a gene encoding a protein of interest;
• (b1) cultivating for a first cultivation phase the Bacillus host cell in said fermentation medium under conditions conducive for the growth of the Bacillus host cell and the expression of the protein of interest, wherein the cultivation of the Bacillus host cell comprises the addition of at least one feed solution and wherein the at least one feed solution provides a carbon source at increasing rates;
• (b2) cultivating for a second cultivation phase the Bacillus host cell culture obtained in step (b1) under conditions conducive for the growth of the Bacillus host cell and the expression of the protein of interest, wherein the cultivation comprises the addition of at least one feed solution and wherein at least one feed solution provides a carbon source at a constant rate, at decreasing rates, or at rates increasing less than the rates in step (b1), wherein said constant rate or the starting rate of said decreasing rates or the starting rate of said rates increasing less than the rates in step (b1) is below the maximum rate of the first cultivation phase;
• and
• (c) separating portions from said Bacillus host cell culture during the cultivation phase at different time points and obtaining the protein of interest from said portions.